Australia's prime minister says this week's deadly cafe attack in Sydney was a "horrific wake-up call" for authorities and may have been preventable.
In an interview with Australian radio Thursday, Prime Minister Tony Abbott also vowed his government will be "swift and thorough" in investigating the attack.
An Iranian-born man armed with a sawed-off shotgun took 17 hostages Monday at the Lindt Chocolate Cafe and held them for 16 hours. He and two of the hostages were killed when police raided the cafe.
The gunman, 50-year-old Man Haron Monis, was out on bail after being charged with being an accessory to his ex-wife's murder. He had also been charged with over 40 cases of sexual assault.
On Wednesday, Abbott announced an investigation into why Monis had been dropped off a terrorist watch list, why he was freed on bail, and why he was able, apparently legally, to acquire a gun.
Monis fled to Australia two decades ago claiming persecution in Iran. He has been referred to in the media as a "self-styled" Islamic cleric, in reference to the non-Islamic practices in which he claimed expertise, including astrology, numerology, and black magic.
The suspected gunman also appeared to be a supporter of the Islamic State group. During the 16-hour siege, Monis made hostages hold up a black flag with an Islamic statement of faith. He also demanded authorities give him an Islamic State flag.
But officials are skeptical that Monis had any links to the Islamist extremist group, saying the attack appears to have been an isolated incident. The Islamic State has repeatedly called for attacks against Western countries, including Australia, for their air campaign to rid its fighters from strongholds in Iraq and Syria.
Australian authorities say dozens of its citizens have gone to the region to fight with the Islamic State, and that many have since returned home. The government has passed a series of tough new laws to counter the threat. But Abbott said Wednesday the system failed to adequately deal with Monis, whom he called a "madman."